Gestation Calculator

This calculator has been designed to give you an idea of the treatment options available to you*. If you decide to have an abortion with Marie Stopes UK, one of our nurses will give a more approximate gestation date during your appointment by way of a scan.
*Please note that this online calculator will only give you an estimated gestation based on the details you have provided.

Please select the first day of your last menstrual period.



We are here to support you 24 hours a day, 7 days a week

Call us now on 0345 300 8090 or email services@mariestopes.org.uk

0345 300 8090

You are here

I'm on the pill but I'm sick or have diarrhoea

Being sick or having severe diarrhoea can affect how well you contraceptive pill works, whether you are taking the combined pill or progesterone-only pill.

If you vomit or have severe diarrhoea within 2 hours of taking the contraceptive pill, it may not have been absorbed by your body. You should consider it as a missed pill, and take another pill straight away. If you are not sick again, the pill will get absorbed and you are protected against pregnancy.

Severe diarrhoea or vomiting for more than 24 hours

If you've had severe diarrhoea or sickness for longer than 24 hours, you should continue taking the pill every day, but use extra contraception such as condoms as well.

If you have been ill and not used other contraceptives, you could be at risk of pregnancy.

Emergency contraception

You may still reduce the risk of an unintended pregnancy by using emergency contraception methods. Emergency contraception is only available for women or girls and comes in two forms, the intra-uterine device or IUD, or the ‘morning after pill'. The IUD is the most effective of the two at preventing pregnancy.

  • The IUD or copper coil is a small plastic and copper device that is fitted into the uterus through the cervix using a simple procedure that takes a few minutes. it stops an egg implanting in the uterus. An IUD can be fitted up to 5 days after unprotected sex, or sometimes later depending on the usual length of your cycle. The IUD is over 99% effective. 

  • This progesterone-only pill is a hormone pill and works by delaying the release of an egg from an ovary, therefore preventing pregnancy.The emergency contraceptive pill or ‘morning after pill’ can be taken up to 120 hours (5 days) after unprotected sex. Effectiveness varies, depending on when in your cycle the sex happened.

Emergency contraception is more effective the quicker you act. If you’ve had unprotected sex, you should visit a Marie Stopes UK clinic, your GP or local sexual health centre as soon as possible.

You should only use emergency contraception in an emergency and not as a regular form of contraception.